Acoustic instrument



1934- G. F. CLARK ET AL 1,969,256

ACOUSTIC INSTRUMENT Filed June 11, 1931 Fig.1.

I v g 9 Fig. 2. 3o

NVENTOR George Fr e dericK LarK, Arthur Stanley Badf'ord,

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Cf 3 m TH ll? ATTORNEY.

Patented Aug. 7, 1934 entree STATES PATENT oFFioEf ACOUSTIC INSTRUMENTGeorge Frederick Clark, West Drayton, and Arthur Stanley Radford,Southall, England Application June 11, 1931, Serial No. 543,592 In GreatBritain June 13, 1930 3 Claims. (Cl. 179-115.5)

Our present invention relates to acoustic intem, as of a dynamicloudspeaker. The coil ends struments of the moving conductor type, asfor 11 and 13, preferably in the usual form of flexible exampleelectro-dynamic loudspeakers. leads connected to the terminals of thecoil 1 may,

It is an object of the present invention to proif desired, be molded inthe skirt 7 and brought 7 vide a robust construction of moving coil forout'at or near the upper edge thereof. In accord- 60 these instruments,particularly for those which nee W h a y Practice, it is desirable t arelarge in size and adapted to handle considerbring the eads 011 Of tmoving Structure at able amounts of power. point thereof suflicientlydistant from the pole According to the present invention, an acoustic ps in Order to p v ta between th 10 instrument of the moving c d t type001m leads and the pole pieces. This has heretofore 65 prises incombination with an acoustic diabeen accomplished y Cement-111gOtherwise Sephragrn, or with a skirt carrying an acoustic curing theleads along the Skirt d adiaphragm, a moving conductor embedded in aphmgmmaterial which does not soften on heating. Pref Although We haveillustrated the Skirt and the 5 erably, the acoustic diaphragm, or theskirt carryleads 11 and 13 as being Within the Gone (1191- 7 ing theacoustic diaphragm, is secured to the mov- Phmgm 9, it is usuallydesirable to reverse the p ing conductor by th same material as that insitions, placing the skirt 7 and the leads 11 and which the movingconductor is embedded, and 13 Outside of the end of the Conethe acousticdiaphragm may comprise a fabric Referring to 2, a coil 1, Wound on aform layer embedded in t same materiaL 3 and molded under heat andpressure into the 75 Th invention is illustrated by way of example massof material 5 which does not soften on subi th accompanying drawing inwhich sequent heating, is mounted in any known or suit- Fig. 1 Shows amoving conductor according to able manner for vibration between thepoles'15, 17 the invention, mounted for co-operation with a ofpet'magnet e The 0011. has suitable magnet system, and secured to askirt to it by the same material 5 as that 1n which the 80 carrying anacoustic diaphragm, while moving conductor 1 is embedded, an acousticdia- Fig. 2 shows a modification of the arrangement phlegm part of whichis Shown at Prefer Shown in ably, the diaphragm 9 consists of thematerial 5 Referring to Fig. 1, an acoustic current coil 1, molded upona fabric layer for example of insulated aluminum wire, wound As aboveSet forth, We Y dlsclesed method on form 3, is molded under heat andpressure of and means for constructing a moving coil and into a mass ofmaterial 5 which, after being thus diaphragm for an electro'dynemicloudspeaker, molded, does not soften on further heating, the having thecharacteristics of rigidity and for 3 acting as the male portion of themold rability under stringent conditions of moisture, 35 Molded to thecoil 1 by means of the material 5 is heat c1191 mechameal SJPTeSSeS- ourimproved- 9'0 a skirt '7 which carries a suitable acousticdiacenstructlon makes posslble the use of a large phragm, part of whichis shown at 9' This skirt diameter moving coil, of relatively smallmass, for '7 may comprise a fabric embedded in the same high D l e e p es that require greater than material which is used in the moving coil at5, and usual ngldlty of the 0011 form to maintain its 40 said samematerial may be used for securing the circular shape especially whensoft wire is used dia hra m to the skirt. the

, R liaterial 5 may be for example, a resin Because of the unitary andrigid nature of the moving coil and its form, there is no tendency forig; the individual conductors to vibrate relative to the .5 not such asBakelite. This material has the remammg movmg structure Furthermore 1O acause of the improved construction of the skirt Wf PTQPeYtY of hemepermanent after and its unitary relationship with the coil form, it iscured, that is, baked under heat and pressure.

and the physical continuity ofconstruction from soften under heat andthe coil structure to the diaphragm, large forces 1t 15 lmpervlolls t0Ordmery Solventsare effectively transmitted from the coil to the Theends 11, 13 of the coil 1 are for connection diaphragm, articularly atthe higher audio frea Suitable Source Of acoustic q y. not quencies,without substantial attenuation. Al-

shown. The coil 1 is mounted in any known though we are not prepared tostate definitely the or suitable manner for vibration in the air gapreason'for attenuation in devices with which we 55 19 between the poles15, 1'7 of a pot magnet syshave been familiar, it is believed that lackof prop- H0 er physical continuity between the moving coil and thediaphragm is a contributing factor.

Having now particularly described and ascertained the nature of our saidinvention, and in what manner the same is to be performed, we declarethat what we claim as new is:

1. In an acoustic instrument of. the moving conductor type, a solenoidalconductor and a skirt element, both said conductor and skirt elementbeingembedded in a material which does not soften on heating. 1

2. In an acoustic device, coil structure constituted by a coil form, asolenoidal conductor about said form, and a skirt elementconcentric:therewith for attaching the coil-structure to a ,dia-

phragm, the conductor, form, and skirt element GEORGE FREDERICK CLARK. vARTHUR STANLEY RADFORD.

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